The present invention relates to an apparatus for mixing or combining a fixed amount of a plurality of powder materials of different ingredients.
In many industrial fields such as medical, phamaceutical and food industries, a plurality of powder materials having different ingredients is combined or mixed in a predetermined ratio with respect to each material.
In a conventional apparatus for measuring and mixing a predetermined amount of the different materials, a number of containers for holding many kinds of materials are provided and a suitable amount of the materials is selectively taken out of the selected chambers into a single mixing container and, similarly, the powder materials of different containers are supplied to the mixing container to be mixed.
However, each container needs a driving system for discharging the material contained in each of the containers. If a great number of containers for holding the materials are necessary, each of the containers needs such a driving system, which necessitates a great amount of cost. Further, if any one of the driving system becomes out of order or inoperable by some reasons, the entire mixing apparatus must be stopped and maintenance and inspection must be continuously done so as to avoid such a failure of the operation, which, however, requires substantial labor and expense.
Further, when the mixing apparatus is entirely controlled automatically, the system for controlling a number of driving devices becomes complex.
The applicant considered the above described problems encountered to the conventional mixing apparatus and proposed some improvements as described in Japanese Patent Application No. 2-42797, filed Feb. 23, 1990, published under Publication No. 3-245830 (unexamined) on Nov. 1, 1991, hereinafter referred to as Japanese publication.
The apparatus disclosed in the Japanese publication has, as shown in FIG. 15, a container device A and a movement device B.
The container device A has, as a basic structure, a container vessel b for containing therein powdery materials, wherein the term "powder materials" used herein intends to include materials in the form of not only powders but also granules and other small particles, and screw conveyer c, and a plurality of the similar container devices A are arranged in series.
The movement device B is disposed along the arrangement of the container devices A. The movement device B has driving device f on a carriage e which is movable along rails d and a container h which is weighed by a weighing device above the driving device f.
The driving device f has a motor i and a connector j, which are reciprocally movable toward and away from the container device A.
The movement device B is reciprocally movable along the length of the rail d and can be stopped at the selected container device A. When the movement device B is stopped at the selected position and the motor is moved forward, the connector j is connected with the connector l of the container device A to rotate the screw conveyer c through sprockets m, n and a chain o.
The screw conveyer c can supply the powder material in the container vessel b to the mixing container h. The supplied powder has been weighed by the weighing device g and, at the predetermined level of the supply, the motor i is stopped. Then the motor i is returned to the original position and the connectors j, l are released to stop the rotation of the screw conveyer c. Thus, the supply of the powder material into the container h is stopped.
Then the movement device B is moved to the next selected container device A and the similar operation of powder supply as described above is carried out.
The container devices A contain different powdery materials, and the predetermined amount of the different powder materials are supplied to the combining container h, which are then mixed and delivered to the production line.
In the apparatus disclosed in the Japanese publication described above, a single movement device B is moved along the plurality of movement devices A and stopped at the selected container devices A to selectively supply different powder materials into the combining container h and, accordingly, it is not necessary to provide a driving mechanism of the screw conveyer c to each of the container devices A.
However, since the container devices A are arranged in the serial direction, the same number of conveyer devices are required as the number of the powder materials so that each material is contained in independent container device if a plurality of materials are combined and, therefore, a great number of container devices A in series arrangement are required, which also requires a large and long installment area and extremely long rails for the movements device B.
The powder materials contained in the container devices b is taken out by the rotation of the screw conveyer c and discharged from the outlet p. The discharge volume of the conveyer c, however, is always fixed and not variable from the start of taking out of the powder material by the start of rotation of the screw conveyer to the end of the taking-out operation by the stop of the screw conveyer c, since the diameter and pitch of the vanes of the screw conveyer is fixed. Thus, it is impossible to change or adjust the discharging volume of the powder materials.
Although the powder materials supplied into the mixing container h is weighed by the weighing device or gage g, the powder material remained adjacent to the outlet p is also discharged by the rotational inertia of the screw conveyer c even after the volume of supply reached the predetermined level and the motor i is stopped. Consequently, more than the predetermined volume of the powder material is supplied, which fails in providing a constant volume of the materials and results in failure in properties of final products.